/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

use euclid::RigidTransform3D;

use crate::{
    ApiSpace, BaseSpace, Frame, InputFrame, InputId, InputSource, SelectEvent, SelectKind,
    WebXrSender,
};

#[derive(Clone, Debug)]
#[cfg_attr(feature = "ipc", derive(serde::Serialize, serde::Deserialize))]
#[allow(clippy::large_enum_variant)]
pub enum Event {
    /// Input source connected
    AddInput(InputSource),
    /// Input source disconnected
    RemoveInput(InputId),
    /// Input updated (this is a disconnect+reconnect)
    UpdateInput(InputId, InputSource),
    /// Session ended by device
    SessionEnd,
    /// Session focused/blurred/etc
    VisibilityChange(Visibility),
    /// Selection started / ended
    Select(InputId, SelectKind, SelectEvent, Frame),
    /// Input from an input source has changed
    InputChanged(InputId, InputFrame),
    /// Reference space has changed
    ReferenceSpaceChanged(BaseSpace, RigidTransform3D<f32, ApiSpace, ApiSpace>),
}

#[derive(Clone, Copy, Debug)]
#[cfg_attr(feature = "ipc", derive(serde::Serialize, serde::Deserialize))]
pub enum Visibility {
    /// Session fully displayed to user
    Visible,
    /// Session still visible, but is not the primary focus
    VisibleBlurred,
    /// Session not visible
    Hidden,
}

/// Convenience structure for buffering up events
/// when no event callback has been set
pub enum EventBuffer {
    Buffered(Vec<Event>),
    Sink(WebXrSender<Event>),
}

impl Default for EventBuffer {
    fn default() -> Self {
        EventBuffer::Buffered(vec![])
    }
}

impl EventBuffer {
    pub fn callback(&mut self, event: Event) {
        match *self {
            EventBuffer::Buffered(ref mut events) => events.push(event),
            EventBuffer::Sink(ref dest) => {
                let _ = dest.send(event);
            },
        }
    }

    pub fn upgrade(&mut self, dest: WebXrSender<Event>) {
        if let EventBuffer::Buffered(ref mut events) = *self {
            for event in events.drain(..) {
                let _ = dest.send(event);
            }
        }
        *self = EventBuffer::Sink(dest)
    }
}